Is there anyway of guesstimating the numbers? I’d say it’s likely that it went supersonic.
Is there a general rule regarding which control surfaces take the most stress when VNE approaches?
As to the first, I agree.
Because of the sampling granularity of both time and altitude ADS-B reporting, it might actually have been just over 17,200 feet in just shy of 3 minutes. So ~5700 FPM. Which is a fairly typical emergency descent in a MAX, so no need to have exceeded anything. Unless it wasn’t a smooth steady state maneuver. At the other limit of sampling granularity it’s ~17,500 in 2 minutes flat = 8,750FPM. That’s seriously fast steady state descent in a MAX. And if it wasn’t steady state, then to achieve that average some must have been faster.
A proper emergency descent in an undamaged airplane is flown with power idle, speedbrakes out, and airspeed snugged up close to Mmo / Vmo = max certificated speed. Which parameters yield a particular VVI depending on weight, temp, etc.
IIRC 6000 FPM is a decent average for a MAX. Which ain’t much. They’re fairly clean and have high residual idle thrust. And have a slowish Mmo/Vmo. All of which multiply together to not being able to descend very quickly. IIRC the 727 could max effort descend at more like 9000 FPM. It was a brick. The tables to look up that info are no longer in our manuals. It was sorta gee whiz info anyhow.
Since power and drag as as favorable as possible, any higher VVI requires a steeper descent and will result in acceleration to a higher equilibrium speed. If you were doing e.g. 6000 FPM & wanted to get to 9000 FPM, so 50% more, your TAS would also have to increase by nearly 50% to match the VVI increase. If you’re just below Mmo /Vmo at M0.82 / 340KIAS that suggests getting up near to to M1.2 and / or 510KIAS. Yikes: those aren’t far from Concorde max speeds.
As to your second question … not that I know of.
IMO the larger problem is flutter, not just direct stress on the surfaces. Once something starts fluttering, it (or most of it) will break off pretty soon. a minute or two tops. I know of no way to predict what might flutter first. The engineers have that test data in their archives, but they don’t share it with the crews.
The evidence we have from the missing parts is that the rudder fluttered first. They managed to recover from the dive without breaking the wings or horizontal tail, and if the tail had been fluttering meaningfully too, then my intuition is they’d have some or all of the elevators instead. And that’d probably have been. Game. Over.
Of course if you pull excessive Gs trying to recover from the dive you can fold the horizontal tail down or the wings up even with no fluttering. Still. Game. Over.
All this is semi-informed spitballing and worth every penny you paid.
Are there any limitations to the dive angle of airliners?
Dive bombers in WWII would attack at extremely steep dives, up to 80° with some models, and as low as 55° with others. Of course, they were special purpose designed and had air brakes to slow their speed.
At a much steeper dive, the same descent would have only taken 30 seconds or so.
It’s not been a good month for helicopters in Los Angeles.
2 dead, 1 missing, 2 hospitalized after medevac chopper crash off Catalina Island
Two people were killed, one person is missing and two were hospitalized after a medevac helicopter crashed into the ocean off Catalina Island Wednesday night, officials with the Los Angeles County Fire Department confirmed.
Not in the sense of a limitation expressed as “Don’t dive beyond 20 degrees nose down”. There might be (or have been) some airliner w a limit like that but I’ve never seen or heard of one from he 4 manufacturers I’m familiar with.
But yes in the sense of …
The steeper the dive the faster you accelerate. And you only have so much ability to retard that acceleration with speed brakes or landing gear extended. And there is a maximum safe speed, after which the airplane gets first hard to control then starts to tear apart.
Said another way, there’s a particular dive angle which amounts to a steady-state descent going at the maximum speed. Any steeper and you’ll soon exceed max speed. If you started out real slow, you could dive more steeply for some few seconds as the speed is building, but would have to bring the nose back up to the steady-state descent angle value as the speed approaches the maximum.
Given the rather weak ability to pull up at very high speeds without pulling too many Gs and breaking the airplane, getting steeply nose low is essentially a suicide move. You can readily get the nose down there. But even if starting from a very slow speed, by the time you get the nose buried steeply, you won’t be able to pull up to level again before you’re waay faster than the speed limit. You may not survive long enough to get the nose fully back up before the airplane falls apart.
Switching gears …
The WW-II dive bombers had very extreme speed brakes to limit accleration in the dive and were inherently high drag airframes to begin with. On the attack, they too ended up in a steady state dive at / near their limit airspeed. It’s just that their very draggy nature let them do that steady state dive at 40, 60, 80 degrees nose down. The airliner hits the same steady state dive at 10-15 degrees nose down.
In modern fighters gravity bombs are dropped anywhere from level to a 45 degree dive. But the nature of the 45 degree drop is you start real high, say 20,000 feet or more above the target, pull the nose down hard towards the target 45 degrees below, pause a second or 3 to refine the aim, drop, and pull off, leveling at maybe 10,000 feet above the target. You’ll still gain 100+ knots in that short time with the nose buried and power at idle. The good news is a fighter has a very high limiting airspeed.
The advantage to the 45 degree drop over flatter ones is entirely that you stay above the range of ground machine gun fire. Doesn’t help for MANPADs or SAMs though. You can get better accuracy and precision from flatter drops done closer to the ground with less-hurried aiming. If the enemy defenses will permit that.
Conversely in WW-II dive bombing was mostly about increasing accuracy, not surviveability. They’d have descended dead vertical if they could have. All in the name of simplifying the many variables needed to drop something from one moving object to hit a different moving object.
Another highly detailed article from Kyra Dempsey (aka Admiral Cloudberg), this time about the 2024 Hop-A-Jet Challenger crash in Florida:
It’s pretty amazing - the engines essentially shut down simultaneously due to suffering the same fault independently. That’s highly, highly unlikely in general. But in this case, it was corrosion brought on by the aircraft being based in a hot area with salt water nearby. That plus several other factors, of course - maintenance procedures and regulations, the intermittent nature of the problems the faults caused, etc.
Great cite!
For those interested, the first half of the article is a stellar explanation of how turbine engines really work. We all know the “suck squeeze bang blow” cartoon-level model, but what happens once you dig under the hood for the next level of how “suck squeeze” really works and how engines accelerate, decelerate, and compensate for changing airspeed, engine speed = RPM, and altitude? They explain all that with great skill without diving too many levels down into the true minutiae.
Sadly, the accident itself appears to be a variant on the same industry-level issue that crashed the UPS MD-11 at Louisville a couple years ago.
Namely that a new machine design is put into service with a bunch of assumptions about how durable it is and how to maintain it. All the manuals and inspection and service schedules are written around those assumptions. Then as experience accumulates, the manufacturer, whether that be GE with the Challenger’s engines or McD-D and later Boeing with the MD-11’s engine mounts, discovers that durability is not as good as expected and things are wearing or aging in ways the inspection and repair procedures do not really take into good account. And then does just about jackshit with that unwelcome knowledge.
With the result that parts wear faster than expected, inspection procedures either come too infrequently or are not looking for the right symptoms, and eventually repairs done per the manual are too little, too late, incomplete, or not even the right thing.
Then something breaks catastrophically and airplanes are wrecked and people are killed.
Any individual operator, even a big one like UPS, is unlikely to have a large enough sample size, nor the analysis chops, to figure out what’s really happening. The manufacturers do. Or should.
An unusual situation: Unpaywalled repost of Washington Post article :
These skydivers parachuted 3,000 feet to help people in a plane crash:
A group of skydivers loaded into a plane at a Wisconsin airport Sunday afternoon, expecting to jump from about 14,000 feet in the air.
But before their plane took off, they saw another plane in the distance fly behind a group of trees. They waited for the plane, a white Beechcraft Debonair, to reappear. It never did. They suspected the Beechcraft Debonair had crashed.
“There really wasn’t much of a discussion about it,” skydiver Sean Plastine said. "It was just, 'People need help. Okay, …
Something that might have helped a plane like the 737 is the horizontal tail plane. The entire tail plane moves to trim the plane. This was the secret to supersonic speed and was first discovered by the British. They failed to test beyond their unmanned “drone” but they were there before the US broke the sound barrier. This is important if the 737 broke the sound barrier. A fully articulated tail plane will not lock up due to the shock wave that builds along it’s surface.
This would be a good time to mention the 1st airliner to break the speed of sound. It was a DC-8 in 1961. And the man who first broke the sound barrier was monitoring the event in an F104. There was so much pressure on the tail plane they had to nose down more to gain control of the trim motor.
Preliminary report is out:
Report at:
Given recent events, was the crash reported on by a news helicopter? And do they have Emergency Float Systems for large helicopters? Seems like a good idea since it’s a regular method of transport from Catalina Island due to their lack of a trauma center.
That’s true of every big jet. All the Douglas, Boeing, Lockheed, and Airbus products since the start of the jet age.
It’s necessary given the large payload and CG range.
Those jets are all still subject to “Mach tuck”. Where the elevator loses effectiveness due to a Mach shock forming ahead of the hinge line. Then the nose drops and it’s game over. The airplane needs both stab & elevator aerodynamically effective to hold the nose up.
For sure the design of a jet tail is intended to push the point of Mach tuck no return to 1.1 or 1.2 to give some margin for overspeeds. Unlike the earlier prop planes with fixed stabs that were screwed at much lower speeds.
Conversely a true supersonic design uses a one piece slab horizontal tail. There is no separately movable stab and elevator. Just a single “stabilator”. Mostly solves the shock problem which solves the tuck problem.
The horizontal tail on a supersonic design is also about 50% larger. Which is about compensating for the rest of the effectiveness loss while the tail is shocked at midchord, rather than the leading edge.
Lotta voodoo there the 1950s engineers sussed out the hard way.
It will be interesting to see what speeds this plane hit.
Oh yeah. That’s probably the number I’m most interested in. Along w the G profile over time.
I don’t know if this was brought up but this video suggests it was a crash axe used in the attack. It’s from NDTV showing pilots in a simulator. I bring this up because almost any knife would have good penetration capacity in comparison to a crash axe which does not have a sharp blade but would deliver more blunt force trauma.
Excellent video, mainly thanks to the passenger telling the story clearly, calmly, and in well-informed detail.
In the YouTube comments, some claim Steeve wasn’t actually interviewing the passenger – that the interview video was from some external source, and Steeve was being deceptive about this.
It’s not especially important, but any thoughts on this?
I’d be surprised – Steeve is a reliable gentleman (and a former lay pastor).
No time to watch it. 
I’ve seen this on celebrity interviews. (Can’t remember which ones.) The celebrity would give one interview, which was distributed to other interviewers who asked questions on a similar set, and the video edited to make it appear that that journalist was conducting the interview.
in the vid, the passenger from 8C mentioned the co-pilot STABBED the pilot (he has very good command of english)…you wouldn’t use the verb STABBED when hitting a person with an axe ..
did I pick that up correctly?: the pilot used the nose wheel as rudder-surrogate (8:00m into the vid) - or was that once they were touched-down? I’d have thought differential thrust would be used for yaw?
I was wondering if a pilot were attempting suicide, if there would be any limitations on the dive angle. The steeper the angle, the quicker the end.
I presume we will find out more about what happened in this particular case, but it sounds like the attack was first then the dive came later.
With the caveat that the lack of survive-ability for glide bombing had an effect on the Battle of Midway, when Marine aviators stationed on Midway tried to attack.
From the Naval History and Heritage Command:
Around 0800, as the Japanese Midway strike force, with many damaged aircraft, neared the Japanese carriers for recovery, a second wave of U.S. bombers from Midway attacked: 16 Marine Corps SBD-Dauntless dive-bombers of VMSB-241, led by squadron commander Major Lofton Henderson (whose name would be immortalized at Henderson Field on Guadalcanal), which had launched after the B-26s, but taken a long time to form up. None of Henderson’s pilots had more than a few hours in the SBD and none had sufficient experience to conduct a true dive-bomb attack. Henderson was forced to lead his squadron on a shallower glide-bomb approach, which both decreased accuracy and increased vulnerability compared to dive-bombing.